256 Mr. T. Davidson's Notes and Descriptions 



Terebratula Morierei, Deslongchamps, MS. PL XIV. 

 fig. 3 & fl, 6. 



Diagnosis. Shell inequivalve, subpentagonal, longer than wide; 

 valves convex, with a deep longitudinal angular sinus or depres- 

 sion in each valve extending from the beak and the umbo to the 

 front, so that at the junction of the two sinuses in front, a deep an- 

 gular notch is produced ; beak rather short, recurved and trun- 

 cated by a largish, circular, entire foramen; beak -ridges well 

 marked, leaving between them and the hinge a well-defined false 

 area ; valves ornamented by numerous squamose, concentric, pro- 

 jecting, imbricated ridges, regularly and closely covering all the 

 surface of the shell. lK>op unknown, most probably short. 

 Structure perforated. Length 9, width 8, depth 6 lines. 



Obs. This curious form of Terebratula was discovered by M. 

 Moriere at St. Honorine des Perthes, near Port-en-Bessin in 

 Normandy, in beds named by M. de Camont Calcaire mar- 

 neu.x de Port-en-Bessin, which, according to M. Deslongchamps, 

 correspond to the Inferior Oolite of Caen. This shell having 

 been presented for M. Deslongchamps' examination, he at once 

 perceived all its remarkable distinctive characters and forwarded 

 his notes and illustrations (fig. 3 of our plate), requesting me to 

 publish the species, which is dedicated to M. Moriere the dis- 

 coverer. 



Ter. Morierei cannot be confounded with any other Jurassic 

 form : at first sight it bears some resemblance to T. coaixtata, 

 but the deep sinus in both valves and the concentric squamose 

 ridges at once distinguish it. 



Plate XIV. fig. 3. From the collection of M. Moriere. 



Terebratula sPHiERoiDALis, Sow. PI. XIV. fig. 2. 



In 1825, Sowerby described, under the name of Ter. spharoi- 

 dalis, a small globose shell found in the Inferior Oolite of Dundry ; 

 but in beds of the same age near St. Maixent (Dep. des Deux 

 Sevres) in France, this species attained such remarkable dimen- 

 sions, that I considered it might be interesting to figure the largest 

 individual I have as yet observed from that locality, now in the 

 British Museum : this magnificent shell is almost circular, 

 and of the dimensions of a billiard ball ; length 24, breadth 22, 

 depth 22 lines. Another in M. Bouchard's cabinet is only 2 

 lines smaller; and specimens of all dimensions have been obtained, 

 some not exceeding 4 lines in length. One of the most curious 

 peculiarities of this species consists in the variations it presents in 

 the junction-line of the valves in front, which is often straight, 

 variously curved, or indented ; having no influence on the regular 

 convexity of the shell, which extends uninterruptedly to the edge, 



